Nucleolar Diameter Research Articles

Nucleolar activity in the fusiform cambial cells of Abies balsamea (Pinaceae): effect of season and age

Nucleolar involvement in the regulation of the activity‐rest‐quiescence cycle of the vascular cambium was assessed by determining the seasonal variation in number, diameter, and volume of nucleoli in fusiform cells of Abies balsamea (L.) Mill. The cells were isolated from 1‐ and 19‐yr‐old cambia and stained with either silver nitrate or Feulgen + naphthol yellow‐S. The ability of fusiform cells to incorporate [5‐3H]‐uridine into nuclei and nucleoli was also determined. In the 1‐yr‐old cambium, the activity of the nucleoli, as evidenced by their diameter, total volume per cell, and intensity of staining with silver nitrate, exhibited two maxima during the year—a large one during cambial reactivation in April‐May and a small one during the rest‐quiescence transition in October. Incorporation of radiolabeled uridine at 20 C was low at the end of the active period and increased during the rest–quiescence transition, suggesting that the quiescent, but not the resting, cambium can rapidly resume nucleolar activity when the temperature is permissive. The number of nucleoli per cell varied between two and eight, and was higher during the dormant than the active period. The increase in number took place during the autumnal activity–rest–quiescence transition, when cambial cells were arrested in the G1 phase of the cell cycle. Similar seasonal changes in nucleolar morphology were observed in the 19‐yr‐old cambium. Nucleolar diameter and total nucleolar volume were larger in the 19‐yr‐old cambium than in the 1‐yr‐old cambium, whereas nucleolar number was lower. Th results suggest that repression of rRNA genes underlies the development of rest when the cambium will not produce new cells.

Nucleolar Activity in the Fusiform Cambial Cells of Abies balsamea (Pinaceae): Effect of Season and Age

Nucleolar involvement in the regulation of the activity-rest-quiescence cycle of the vascular cambium was assessed by determining the seasonal variation in number, diameter, and volume of nucleoli in fusiform cells of Abies balsamea (L.) Mill. The cells were isolated from 1- and 19-yr-old cambia and stained with either silver nitrate or Feulgen + naphthol yellow-S. The ability of fusiform cells to incorporate [5-3H]-uridine into nuclei and nucleoli was also determined. In the 1-yr-old cambium, the activity of the nucleoli, as evidenced by their diameter, total volume per cell, and intensity of staining with silver nitrate, exhibited two maxima during the year—a large one during cambial reactivation in April-May and a small one during the rest-quiescence transition in October. Incorporation of radiolabeled uridine at 20 C was low at the end of the active period and increased during the rest–quiescence transition, suggesting that the quiescent, but not the resting, cambium can rapidly resume nucleolar activity when the temperature is permissive. The number of nucleoli per cell varied between two and eight, and was higher during the dormant than the active period. The increase in number took place during the autumnal activity–rest–quiescence transition, when cambial cells were arrested in the G1 phase of the cell cycle. Similar seasonal changes in nucleolar morphology were observed in the 19-yr-old cambium. Nucleolar diameter and total nucleolar volume were larger in the 19-yr-old cambium than in the 1-yr-old cambium, whereas nucleolar number was lower. Th results suggest that repression of rRNA genes underlies the development of rest when the cambium will not produce new cells.

Atypical basal cell hyperplasia of the prostate. Immunophenotypic profile and proposed classification of basal cell proliferations.

Prostatic basal cell proliferations range from focal basal cell hyperplasia (BCH) to florid adenoid basal cell tumor (ABCT). We reviewed 36 cases of basal cell proliferation to evaluate the architectural and cytologic spectrum of these lesions and identified four distinct patterns by light microscopy: BCH, 12 cases, including two cases with stromal sclerosis; atypical BCH with nucleolomegaly, eight cases; basal cell adenoma (BCA), nine cases; and ABCT, seven cases. Twenty-three cases were evaluated immunohistochemically, and all displayed cytoplasmic immunoreactivity in basal cells with basal-cell-specific high-molecular-weight keratin 34 beta E12 but with increased staining in BCH compared with that in BCA and ABCT. Prostate-specific antigen and prostatic acid phosphatase reactivity were seen at least focally in all cases except two cases each of BCA and ABCT. Chromogranin, S-100 protein, and neuron-specific enolase reactivity were rare or negative in all cases. Nucleolar diameter, measured in 18 of the 36 cases, was significantly greater in atypical BCH (mean, 1.96 microns) than in other forms of basal cell proliferation (mean, < 1.0 microns) (P < 0.05). These results indicate that on the basis of light microscopic, immunohistochemical, and morphometric findings, the spectrum of basal cell proliferations in the prostate can be separated into four distinct groups: BCH, atypical BCH, BCA, and ABCT.

Cytologic diagnosis of non-oxyphil follicular neoplasias of the thyroid: Multivariate Classification Procedure Based on Quantitative Nucleolar Features

The study was done on cytologic material of 58 non-oxyphil follicular neoplasias of the thyroid, 32 of which were adenomas and 26 carcinomas. Three groups of nucleolar features were quantified using a routine microscope with an ocular micrometer: frequency-, size-, and margination-related features. Since value overlap was present between two categories for all the variables, stepwise discriminant analysis was applied. The following three features were selected by the computer for calculation of one canonical discriminant function: percentage of marginated nucleoli, percentage of nuclei with one nucleolus, mean major nucleolar diameter. The percentage of agreement between morphologic and computer classifications was 95%. Two follicular adenomas were allocated to the carcinoma category, whereas one follicular carcinoma was allocated to the adenoma category. Out of 58, 52 were diagnosed by the computer into one of the two diagnostic categories with a very high probability, i.e. P greater than 0.75, the remaining 6 being considered intermediate.

Value of quantitative nucleolar features in the preoperative cytological diagnosis of follicular neoplasias of the thyroid.

Nucleolar prevalence, size, and outline were investigated on cytological material from cold thyroid nodules obtained by fine needle aspiration. The percentage of nucleolated nuclei in follicular adenoma (32 cases) was less than in follicular carcinoma (26 cases). In adenoma most nuclei contained one nucleolus, and nuclei with two or more nucleoli were less common than in carcinoma where most cases showed the highest nucleolar diameter values. There was some overlap between adenomas and carcinomas, however, when the mean of the 10 largest values of the major nucleolar diameter was considered. In follicular carcinoma the percentage of marginated nucleoli--that is, those touching the nuclear membrane--was, in general, greater than 20%; in adenoma the values were equal to or lower than 16%. The overlap index showed that the percentages of marginated nucleoli and nucleolated nuclei are the two best discriminatory features between adenoma and carcinoma.

Nucleolar Organizer Regions (NOR) in Hyperplastic and Neoplastic Prostate Disease

Nucleolar organizer regions (NOR) are DNA loops encoding ribosomal RNA production. Detectable by the argyrophilia (AgNOR) of associated proteins, AgNOR numbers correlate with growth fraction and may have diagnostic and prognostic utility in human tumors. Because nucleolar size is important in the diagnosis of prostate carcinoma, we compared AgNOR counts in benign, atypical, and malignant prostate lesions and correlated them with nucleolar diameter. We counted AgNOR in benign prostatic hyperplasia, atypical adenomatous hyperplasia, intraductal dysplasias, and carcinomas of various Gleason grades. The mean AgNOR count per nucleus for benign prostatic hyperplasia nuclei was 4.51; for atypical adenomatous hyperplasia, 5.64; for intraductal dysplasias, 7.35; for carcinoma of Gleason grades 2 + 3, 8.87; and for carcinoma Gleason grades 4 + 5, 10.42. Counts in the carcinomas and intraductal dysplasias were significantly different from those of benign prostatic hyperplasia. Mean AgNOR counts of the carcinomas and intraductal dysplasias did not overlap with those of benign prostatic hyperplasia, suggesting that intraductal dysplasia shares more with carcinoma than benign prostatic hyperplasia. Nucleolar diameters increased from benign prostatic hyperplasia to atypical adenomatous hyperplasia, intraductal dysplasias, and the carcinomas, correlating with increasing AgNOR counts. Nucleolar diameters in the carcinomas were significantly different than those of benign prostatic hyperplasia; those in intraductal dysplasias were not. Our findings suggest that AgNOR counts are superior to nucleolar diameters alone in separating intraductal dysplasias from benign prostatic hyperplasia but provide no additional information in diagnosing carcinoma.

Correlation study of serum prolactin levels, pituitary weights, number and ultrastructure of pituitary lactotrophs in female long-evans rats

Twenty-five female, 23-month-old Long-Evans rats were sacrificed for investigation of correlations between serum prolactin levels, pituitary weights, numbers and ultrastructural features of pituitary lactotrophs. Serum prolactin levels measured by radioimmunoassay varied from 7.1 ng/ml to 1,534.0 ng/ml. Pituitary weights ranged from 16.0 mg to 255.0 mg. Serum prolactin levels were increased when pituitary weights were high; statistical analysis revealed a correlation between the two. No significant correlation was evident between serum prolactin levels and lactotroph percentage and ultrastructure. Light microscopy revealed a large number of lactotrophs in almost every pituitary. Values for nuclear, cell and cytoplasmic areas, nuclear/cytoplasmic ratios and nucleolar diameters remained similar in the lactotrophs of all animals. Electron microscopy disclosed no lactotroph damage or vascular injury. Ultrastructural morphometry of lactotrophs in the pituitaries studied showed no major differences in cytoplasmic volume densities of endoplasmic reticulum, Golgi complex, mitochondria, secretory granules and lysosomes as well as secretory granule diameters. It is reasonable to conclude that elevations of serum prolactin levels are due to an increase in pituitary mass, resulting from accumulation of lactotrophs. Thus hyperprolactinemia appears to be secondary to an increase in the number of lactotrophs and not hyperactivity of individual cells.

Nuclear behavior during sporulation of the true slime mold Didymium nigripes

Nuclear behavior during sporulation of the true slime mold Didymium nigripes Fries includes extensive episodes of nuclear degeneration of a magnitude not previously suspected, two mitotic divisions, and changes in nuclear morphology. Nuclear and nucleolar diameter are reduced and up to 60% of the nuclei present at the onset of sporulation degenerate. Didymium nigripes possesses nuclei of several ploidy levels throughout its life cycle, and ratios of these nuclear size classes change in random fashion during sporulation, presumably as a result of nuclear degeneration. This study demonstrates that the end result of nuclear degeneration is not the elimination of a single size class of nucleus.

Quantitative analysis of Sertoli cells in neonatally oestrogen-treated rats.

On Day 1 of age rats were treated with 500 micrograms oestradiol benzoate. Oestrogen-treated rats had increased numbers of Sertoli cells per reference area or volume, whereas the total number of cells per testis was unchanged. The mean nuclear size was significantly smaller in oestrogen-treated rats than in control rats, at 22 and 45 days of age. The volume density of the heterochromatin clumps decreased from 22 to 45 days of age in control rats (68% fall), the decrease being slower in oestrogenized animals (30% fall) during the same period. The differences were significant at 45 days of age only. The relative volume occupied by the nuclear membrane infoldings was significantly less in oestrogenized rats than in control ones at the two ages considered. Nucleolar development was delayed in oestrogen-treated rats, which had lower numbers of nuclear sections showing nucleoli, as well as a decrease in the nucleolar diameter. We suggest that these Sertoli cell alterations are due to the altered gonadotrophin and testosterone concentrations induced by the steroid treatment rather than to a direct effect of oestrogen.

The relation of nucleolus diameter to cell body diameter in mammalian dorsal root ganglion cells.

The present study correlates cell body and nucleolar sizes for dorsal root ganglion cells in the rat. To do this, we measured cell body areas and calculated their diameters and measured nucleolar diameters for 719 cells. These data indicate that there is a correlation in that increasing cell size is associated with increasing nucleolar size. However, there is considerable variability of cell body size for each nucleolar diameter and vice versa. Nevertheless, when nucleolar diameters are grouped, the function 1n D = 1.687 + 0.334 dr, where D is the diameter of the cell body and dr the rounded diameter of the nucleolus, produced an almost straight line. Thus this formula provides a good estimate of the relation of nucleolar and cell body sizes for dorsal root ganglion cells of the rat. In addition, estimates of the variances of cell body size at each nucleolar diameter are provided.

The determination of an empirical correction factor to deal with the problem of nucleolar splitting in neuronal counts

Nucleolar counts are the method of choice for determining neuronal numbers. The main problem is the determination of an accurate correction factor for split nucleoli. The difficulties are that small nucleolar fragments are often unrecognizable and that nucleoli may be pushed or rolled rather than cleanly cut by the knife. A widely used method uses an estimate to account for the difficulties, and almost all methods depend on measurements of such things as section thickness and nucleolar diameters. We differ from previous procedures by identifying neurons first and then determining whether the nucleolus in each identified neuron is split or whole. If N is the true number of neurons, n the number of nucleoli counted to estimate N, T the number of nucleoli counted for the correction factor and S the number of nucleoli in T that are split, then N = [(T-S/2)/T]× n. The advantages are that the observations are easily done and that there are no estimates, only a determination of the numbers of whole and split nucleoli for a sample population of neurons.

The effects of constant light and constant darkness on daily changes in the morphology of the pineal organ in the goldfish, Carassius auratus.

The fine structure of photoreceptor cells in the pineal organ of the goldfish was found to vary quantitatively over a 24-hour period. Stereological analysis revealed significant daily changes in the volume of the cell and inner segment, nuclear volume and nucleolar diameter, volume of endoplasmic reticulum and Golgi bodies, area of both rough and smooth endoplasmic reticulum, and number of vesicles associated with each Golgi body. Peak values of these variables occurred either during the dark phase or latter part of the light phase. These findings agree closely with those reported in higher vertebrates, and suggest that metabolic activities, and possible secretory functions, of the pineal organ of fishes are synchronized to the light:dark cycle. Daily changes in these variables generally persisted in fish exposed to constant darkness for seven days, with the peak in these rhythms coinciding closely with those observed in fish exposed to a light:dark cycle. In contrast, the rhythms in all variables were abolished in fish kept in continual light for seven days. Photoreceptor cells from fish exposed to continuous light had larger nucleoli and greater amounts of rough endoplasmic reticulum indicating a further effect of light on pineal metabolism in lower vertebrates.

Transmission blockade during neuronal development. Observations on the trochlear nucleus with quantitative histological methods and with ultrastructural and axonal transport studies in the chick embryo.

Transmission blockade has been performed with α- and β-bungarotoxin and with d-tubocurarine in ten to eighteen-day-old chick embryos. Prevention of the naturally occurring nerve cell death in the trochlear nucleus after postsynaptic blockade is reported. Using stereological and biomathematical methods, it was possible to describe an absolute enlargement in volume of the trochlear nucleus despite a significant overall decrease in brain weight after α-bungarotoxin and d-tubocurarine treatment. Nuclear and nucleolar diameters and the number of nucleoli per cell nucleus in trochlear neurons show time-dependent changes, but not differences between the controls and curare treated chick embryos. The ultrastructural appearance of trochlear neurons is not different between the controls and curare treated embryos after eight days of transmission blockade, indicating a similar maturation in these two groups. Only a somewhat higher frequency of dense bodies has been found after curare treatment. In contrast to these findings, the electron micrographs of β-bungarotoxin treated chick embryos show severe degenerative signs in the trochlear nucleus and other motor brain regions very similar to the morphological changes after axonal lesions (retrograde axonal reaction). The quantitative Golgi-analysis of trochlear neurons demonstrates a significant decrease in dendritic branching after curare treatment. All neurons in the trochlear nucleus are labeled by retrograde transport of horseradish-peroxidase after injection into the upper extraocular muscles both in the controls and curare-treated animals. Therefore, we can assume that the motor neurons have maintained contacts with their peripheral target even after eight days of transmission blockade.

Age related decrease in nuclear and nucleolar size in hypodermal cells of the rotifer

With advancing age, there is a continuous and significant decrease in the diameter of both nucleus and nucleolus in hypodermal cells of the rotifer, Asplanchna brightwelli. The decrease in nucleolar diameter is most pronounced (63%) and may be related to a decrease in synthetic activity of these cells. The nucleus decreases in diameter by 25% during the 6 day lifespan of the rotifer. Decrease in nuclear size may be characteristic of ageing both in long-lived and in short-lived post-mitotic cells.

Quantitative morphology and environmental responses of the pineal gland in the collared lemming (Dicrostonyx groenlandicus).

Collared lemmings from Churchill, Manitoba, and their descendants were studied in captivity to define neuroendocrine and related histophsiological characteristics and responses, particularly in relation to photic and temperature conditions. Relatively great pineal size (0.1755 +/- 0.0167 mm3, or 3.08 +/- 0.30 = pineal volume in mm3 X 10(3)/body weight in gm; N = 16) shown in this arctic rodent is consistent with the suggestion that pineal size and significance may tend to be greater in more northern (higher latitude) species. Total number of nucleated cells per pineal averaged 137,000 +/- 10,500. Pinealocytes (105,000 +/- 8,700/pineal) and other cell types were present in relative numbers typical of mammalian pineal glands, and were not numerically correlated with age, sex, or location or circumstances of birth and early postnatal life. Chronic exposure to warmer (21-27 degrees C) in comparison with colder (-9 to -6 degrees C) environments, whatever the illumination, led to greater pinealocyte activity, as shown especially by nucleolar diameter, throughout most of the nine regions of the organ analyzed cytologically (all regions combined: P less than 0.001). Increased pinealocyte activity in chronic darkness was suggested by similar evidence (P less than 0.01), but in comparison with the thermal effects, was less marked and more variable in different regions of the organ. These and other findings of this study indicate that the Dicrostonyx pineal organ is morphologically unique, relatively large in size, and cytologically responsive to environmental conditions.

Methylcholanthrene induced murine primitive neuroectodermal tumor: ultrastructure and nuclear RNA polymerase activity.

The histology, ultrastructure, and nuclear RNA polymerase activity are described in a murine primitive neuroectodermal tumor derived by serial transplantation from a tumor originally induced with methylcholanthrene and classified as an ependymoblastoma. The light microscope and ultrastructural studies show that this tumor does not contain the distinguishing morphological features of differentiated ependymal cells which are also commonly seen in human ependymomas. One outstanding feature is the size and number of the nucleoli. The mean number of nucleoli/nucleus is 4 which is two to four times that of the normal neuroglial cell. The nucleolar diameter is about twice that found in normal neuroglial cells. The nucleolar diameter is about twice that found in normal neuroglial cells. The nuclear RNA synthesizing activity is the highest of the chemically induced animal tumors we have studied. The alpha amanitin inhibition is the lowest seen in any of these tumors which suggests that RNA polymerases inhibited by alpha amanitin contribute less to the total nuclear RNA synthesis. Adriamycin significantly inhibits the nuclear RNA polymerase activity of this tumor.

Quantitative analysis of the Callender classification of uveal melanoma cells.

Six experienced ophthalmic pathologists independently classified 90 uveal melanoma cells according to the Callender classification. They frequently disagreed among themselves, but at least four of the six agreed on the classification of 77 cells. In an effort to delineate those cytologic features that are most useful in the application of Callender classification, 12 factors were evaluated for each of these cells. Multivariate analysis (MVA) proved that six factors (chromatin clumping, minimum nuclear diameter, nucleolar diameter, chromatin margination, maximum nuclear diameter, and abundant cytoplasm) were useful for determining the cell type selected by the majority of pathologists, although some cells could not be sharply classified. It was concluded that uveal melanoma cells occupy a continuous cytologic spectrum, from benign-appearing spindle A cells to very malignant-appearing epithelioid cells.

Seasonal cycle and physiological correlates of pinealocyte nuclear and nucleolar diameters in the bats, Myotis lucifugus and Myotis sodalis

An annual or seasonal cycle was suggested in the activity of pinealocytes of bats ( Myotis lucifugus and M. sodalis) collected at the same place within the same cave (Bat Cave, Carter Co., Ky.) at six times of the year. Seasonal changes were statistically significant in both pinealocyte nuclear and nucleolar diameters, but the greatest amplitude and consistency of change were in the latter. The annual peak in nucleolar size occurred in March, at about the time of arousal and dispersal from hibernation. The nadir occurred in early fall just before hibernation. The pattern of seasonal changes in pinealocyte activity suggested by nucleolar size is the inverse of that of pituitary LH cells in related species. Experimental evaluation of a possible pineal role during or following spring arousal and dispersal of bats is suggested in the light of recent studies showing a pineal contribution to regulation of the timing of sympatheto-adrenomedullary activity in laboratory rats.

Semiautomatic morphometric analysis of the nucleolar development in the nucl. n. oculomotorii of Tupaia belangeri during ontogenesis.

The development during ontogenesis of the nuclear and nucleolar diameters and of the numbers of nucleoli per nucleus in the nucl. n. oculomotorii of 32 male Tupaia belangeri are described. The measurements of the nucleolar diameters were done automatically using the Micro-Videomat (Zeiss, Oberkochen). Increase of the nuclear and nucleolar diameters yielded a nearly sigmoid-shaped curve, which was fitted using the logistic growth function. The "ideal" value of the nucleolar diameter is 3.7 mum with a half value time of 22 days of ontogenesis and an enlargement factor of 1.53. The respective parameters for the nucleus are 12.2 mum, 28 days and 1.27. The ratio of the nuclear to nucleolar diameters decreases exponentially during ontogenesis to a value of 3.3. The validity of these easily determinable morphologic parameters for the RNA-synthesis is discussed. The number of nuclei with 2 or 3 nucleoli decreases during ontogenesis. The relevance of this fact for cell counting is also discussed.

Embryogenesis of Calliphora erythrocephala

Ultrastructural changes in midgut epithelial cells of Calliphora during the last nine hours of development are described on the basis of a division into four stages. The midgut differentiates into three parts, the anterior midgut part (AMP), the mid-midgut part (MMP), and the posterior midgut part (PMP). The ultrastructure and the developmental changes in it are practically the same in AMP and PMP cells, but the MMP cells show a different pattern. The lateral membrane junctions are more extensive in the MMP than in the AMP and PMP, but the brush-border of MMP cells is less developed. Variations in the number, size, and electron density of vesicles presumably derived from Golgi regions are larger in this part of the midgut than in other parts. Mitochondrial length increases in all three parts of the midgut, as do the nuclear and nucleolar diameters, attended by an increase in the amount of RER.